Machine for transmitting sound over long distances.



'APPLICATION FILED APR- 24, 1913-.

Patented Mar. 28,1916.

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i WALTER OPEL, 0F LEIIEZIG, GER-m.

MACHINE FOR TRANSMITTING SOUND OVER LONG DISTANCES.

Lavinia.

Specification of Letters Patent. Pgfignfigd Itfiap, g& 1916,,

Application filed April at, 1913. Serial No. 763,425.

which the sound waves are transmitted over long distances. For the purpose-of transmitting the'sound waves of a talking machine overlong distances, use is generally made of sound boxes constructed each in the ciently audible tone transmission owing to the factthat the required strengths of currents necessary for this purpose produce disturbing heateiiects in the sound-box and even in the stylus. These heat effects may rise to such a degree as to cause damage to the record or even destroy it.

It is the special purpose of the present in-, vention to obviatethe described drawbacks.

This has been primarily attained for the distant transmission of sound by the provision of heatinsulating means on the sound-box, as will be more clearly understood from a description of the accompanying drawings in which:

Figure 1 represents in elevation, partly in section, a sound-box of a talking machine embodying in desirable form-the present improvements. Fig. 2 is a front view of the same. Figs. 3 and 4 illustrate two difierent constructions of a double sound-box of this kind. 7 a

Similar characters of reference denote like The microphone cell of the sound-box shown consists of a casing A containing a filler or charge'B of carbon particles or the like which are located between the two plates C and D. Adjoining the plate (3 there is a cover plate E which carries a socket that arm of the talking According to the present invention the casing A of the sound-box is provided with a number of heat insulating members F, of which four are shown, in Fig. 2. These members maybe connected by a common ring-G which at the same time serves asa protective jacket enabling the operator to grasp the sound-box should it be heated by thecurrent traversing it. -This is rendered possible because the transmission of heat to the ring G is prevented by the insulating members F. The ring G may be perforated or otherwise so constructed as to increase the air cooling action. These heat insulating members are advantageous for the operator in ha-ndlingthe sound box and indirectly aid in supporting the terminal M. The arm H may be supported on the ring G, which holds the heat insulating members Fin position. In this instance, the arm or stylus support H is preferably arranged so as to'oscillate about its supporting pivot I. The transmisform of a microphone. However, it is not. I possible with such means to obtain a suifi sion' of heat through 'the pivot of .the arm H is prevented because it is mounted on the ring G which in'turn is connected tothe heat insulating members F. The transmission of heat through the annH is"not"great under any" circumstances because this arm consists of a thin metal body which radiates heat rather quickly. 7 v i In order to minimize the transmission of heat in accordance with the present invention the coveringplates C, D of the soundboX are not made of-metal sheeting but consist of carbon disks and to secure them at a certain distance a ring K of asbestos is interposed, as shown in Figs. 1 and 2. By virtue of these carbon disks the transmission of heat is considerably reduced, on the one hand, to the arm H and on the other hand to the metal plate E on whichwthe socket oscillating in two directions, one pcrpendicular to the other and transmitting its vibration through the arm H to the carbon plate D. It is evident that the arm'H may he supported. directly on an insulating member 15 instead of being supported on the ring G" which holds the insulating members F in position.

y In order to counteract overcharging and consequently the weakening of the tone strength and to render it possible to employ a relatively large number of reproducing apparatuses, a multiple of sound-boxes, as hereinbefore described, may be arrangedin series and made operative by means of a stylus common to all. In. this case. a special circuit preferably is provided for each sound-box so as to act on a separate group of tone reproducing devices, or the soundboXes may be arranged in multiple arc in one circuit, if desired. According to the arrangement, diagrammatically shown in Fig.

3, two sound-boxes with casings A A are arranged parallel to one another and the stylus L, through the intermediary of the arm H, is

adapted to act simultaneously on the carbon f The branching of the plates of both boxes. circuit is made, at the source of electricity N, in two directions, one extending to the group of apparatuses 0 through the sound-box A .and the other to a similar group of apparatuses P through the sound-box A In the arrangement diagrammatically shown in Fig. 4:, the sound-boxes A, A are arranged side by side and the stylus L acts on the carbon plates through the intermediary of forked arms H H I claim as my invention:

1. A device for long distance transmission of sound comprising a sound-box with a microphone cell, heat'insulating means thereon, a stylus supporting bar on the soundbox, a pivot on which the bar oscillates, said bar and pivot being insulated against heat.

from the microphone cell by the heat insulating means, and astylus in the oscillating bar. r

2. A device for long distance transmission of sound comprising a sound-box with a microphone cell, heat insulating means on the sound-box, means for holding said heat insulators in position, an electric terminal on the heat insulator holding means, a stylus supporting bar on the sound-box, a pivot on of sound comprising a sound-box with a microphone cell, a multiple of separate heat insulating means on the sound-box, a ring or jacket holding the heat insulating means in position, a stylus supporting bar on the sound-box, a pivot on which said bar oscillates, said bar and pivot being insulated against heat from the microphone cell by the heat insulating means, and a stylus in the os- 'cillating bar.

5. Adevice for long distance transmission of'sound comprising a sound-box with a microphone cell composed of an asbestos ring, carbon plate covers, and a casing, a multiple of heat insulating members on the sound box separated from the asbestos ring by the casing, a stylus supporting bar on the soundbox, a pivot on which said bar oscillates, said bar and pivot'being insulated against heat from the microphone cell by the heat .i'nsulating members, and a stylus in the oscillating bar.

6. A device for long distance transmission of sound comprising a sound-box with a microphone cell, a multiple of heat insulating members on the sound-box, a ring or jacket for holding said heat insulating members in position, a stylus supporting bar on the sound-box, a pivot supported on said ring on which the bar oscillates, said bar and pivot being insulated against heat from the micro,- phone cell by the heat insulating means, and a stylus in the oscillating bar.

' In testimony whereof I have aifixedmy signature in presence of two witnesses.

- WALTER OPEL. Witnesses RUDOLPH FRIoKn, TRAUGATT OPEL. 

